1. Field of the Invention
The present invention relates to a tape reel and a take-up reel on which is wound a recording tape, such as a magnetic tape or the like, which is used as a recording/playback medium mainly of computers or the like, and to a recording tape cartridge which accommodates the tape reel within a case, and to a drive device which is provided with the take-up reel and into which the recording tape cartridge is loaded.
2. Description of the Related Art
There are conventionally known recording tape cartridges in which a recording tape, such as a magnetic tape or the like which is used as a data recording/playback medium (for data backup) of computers or the like, is wound on the hub (core portion) of a reel (tape reel), and the reel is singly accommodated within a case. When the recording tape cartridge is loaded into a drive device, the recording tape is pulled out via a leader member from an opening provided in the recording tape cartridge. The pulled out recording tape is, via tape guides and a recording/playback head, taken-up onto a take-up reel within the drive device.
There has been conventionally disclosed, at a reel or the like on which such a recording tape is wound, causing the width direction central portion of the hub for example to swell-out (be formed in a convex shape) so as to form a substantial barrel shape, as shown in Japanese Patent Application Laid-Open (JP-A) No. 6-309837 for example. Further, as shown in JP-A No. 2001-118358 for example, a reel at which a portion (a maximum diameter portion), whose outer diameter is larger than the outer diameter at the both end portions, is formed at the outer peripheral surface of the hub in this way, is manufactured by forming the hub and flanges by injection molding a plastic material such as polycarbonate (PC), polyacetal (POM) or the like, and thereafter, assembling them by adhesion, welding, snap-fitting (the engagement of claws) using elasticity, or the like.
However, when an attempt is made to form the shape of a hub which is molded by injection molding into a substantial barrel shape for example, there is the problem of so-called undercut (a shape which cannot be ejected out from the mold at the time of release from the mold after molding). Further, due to so-called sink mark, non-uniformity of the molding pressure distribution, non-uniformity in cooling, effects due to the shape or wall-thickness, or the like, the shape of the outer peripheral surface of an injection-molded hub becomes taper-shaped, hourglass-shaped, or a complex shape combining these, and a shape such as a barrel or a pot or the like cannot be accurately realized by injection molding.
As methods for overcoming this, a method of providing the parting line at the maximum diameter portion of the hub, and a method of providing parting portions at plural places in the widthwidth direction (the heightwise direction of the hub) and providing the mold with a sliding mechanism have been thought of. However, in such methods, a parting line arises at the outer peripheral surface of the hub around which the recording tape is wound, and a step or burrs arise at this portion, and there is the concern that cutting, damage or deformation or the recording tape, or damage or destruction of servo signals and data (information) due to damage or deformation will arise. Namely, there is the concern that such problems will cause the occurrence of servo tracking errors or errors in the recording and playback of information.
Further, due to the increasing of capacities in recent years, there has been the trend to make a recording tape T thinner, and the strength thereof also decreases. Therefore, it has become even easier than before for recording tapes to be damaged, deformed, or cut. Moreover, as shown in JP-A No. 2001-118358 for example, a method has also been conceived in which the hub and the upper and lower flanges are manufactured by respectively being molded independently, and only the hub is formed in a substantial barrel shape or the like by cutting. However, not only is it necessary to form the hub in a substantial barrel shape or the like, but there is also the need to form positioning configurations for engagement with the upper and lower flanges and a drive device at the both end portions of the hub, and therefore, there is the problem that the manufacturing cost increases several-fold. Further, take-up reels are provided at drive devices as well, and the same holds for take-up reels as well.